LONDON (AP) - Britain's Supreme Court has endorsed the extradition of WikiLeaks chief Julian Assange to Sweden, bringing the secret-spilling Internet activist a big step closer to prosecution in a Scandinavian court.

But a question mark hung over the decision after Assange's lawyer made the highly unusual suggestion that she would try to reopen the case, raising the prospect of more legal wrangling.

Assange, 40, has spent the better part of two years fighting attempts to send him to the Sweden, where he is wanted over sex crime allegations. He has yet to be charged.

The U.K. side of that struggle came to an uncertain end Wednesday, with the nation's highest court ruling 5-2 that the warrant seeking his arrest was properly issued - and Assange's lawyer saying she might challenge the ruling because it made reference to a treaty whose interpretation she says she did not have the chance to challenge.

Supreme Court President Nicholas Phillips, speaking for the majority, acknowledged that coming to a conclusion had "not been simple."

But he said that the court had ultimately concluded that "the request for Mr. Assange's extradition has been lawfully made and his appeal against extradition is accordingly dismissed."

Assange won't be sent to Sweden immediately.

His lawyer, Dinah Rose, stood up after the verdict to say that court's ruling was based on evidence that was not argued during the appeal, requesting time to study the verdict further with an eye toward trying to reopen the case.

Such a maneuver is practically unheard of, according to attorney Karen Todner, whose law firm handles many high-profile extradition cases.

"It's very unusual," she told The Associated Press. "I've never known them to reopen a case."

Phillips gave Rose two weeks to apply to make her move, meaning an extradition wouldn't happen until the second half of June at the earliest.

It could be much later. Even if the Supreme Court refuses to revisit its judgment, Assange could appeal to the European Court of Human Rights, although Todner said that would be unlikely to do much unless he could argue that his physical safety or psychological well-being would be at risk in Sweden.

Assange, a former computer hacker from Australia, shot to international prominence in 2010 with the release of hundreds of thousands of secret U.S. documents, including a hard-to-watch video that showed U.S. forces gunning down a crowd of Iraqi civilians and journalists that they'd mistaken for insurgents.

His release of a quarter-million classified U.S. State Department cables in the final months of that year outraged Washington and destabilized American diplomacy worldwide.

But his work exposing government secrets increasingly came under a cloud after two Swedish women accused him of molestation and rape following a visit to the country in mid-2010. Assange denies wrongdoing, saying the sex was consensual, but has refused to go to Sweden, claiming he won't get a fair trial there.

He and his supporters have also hinted that the sex allegations are a cover for a planned move to extradite him to the United States, where he claims he's been secretly indicted for the WikiLeaks disclosures.

Those allegations, paired with the ponderous progress of Assange's appeals, have caused irritation in Sweden.

Claes Borgstrom, the lawyer who represents the two Swedish women who accuse Assange of sex crimes, expressed relief at the U.K. Supreme Court's decision, but said the British judicial system should have dealt with the case more quickly.

"Now, finally, we have a decision," Borgstrom told AP, saying the long wait had been stressful for his clients. He dismissed suggestions that the underlying motive behind the extradition is to hand Assange over to the United States.

"He is not at a greater risk of being handed over from Sweden than from Britain," Borgstrom said.

Unusually, Assange did not appear in court Wednesday - he was reportedly stuck in traffic. Attempts to reach him for comment weren't immediately successful.